ExEP Science Plan, Rev A JPL D: 1735632 Release Date: February 15, 2019 Page 1 of 61 Created By: David A. Breda Date Program TDEM System Engineer Exoplanet Exploration Program NASA/Jet Propulsion Laboratory California Institute of Technology Dr. Nick Siegler Date Program Chief Technologist Exoplanet Exploration Program NASA/Jet Propulsion Laboratory California Institute of Technology Concurred By: Dr. Gary Blackwood Date Program Manager Exoplanet Exploration Program NASA/Jet Propulsion Laboratory California Institute of Technology EXOPDr.LANET Douglas Hudgins E XPLORATION PROGRAMDate Program Scientist Exoplanet Exploration Program ScienceScience Plan Mission DirectorateAppendix NASA Headquarters Karl Stapelfeldt, Program Chief Scientist Eric Mamajek, Deputy Program Chief Scientist Exoplanet Exploration Program JPL CL#19-0790 JPL Document No: 1735632 ExEP Science Plan, Rev A JPL D: 1735632 Release Date: February 15, 2019 Page 2 of 61 Approved by: Dr. Gary Blackwood Date Program Manager, Exoplanet Exploration Program Office NASA/Jet Propulsion Laboratory Dr. Douglas Hudgins Date Program Scientist Exoplanet Exploration Program Science Mission Directorate NASA Headquarters Created by: Dr. Karl Stapelfeldt Chief Program Scientist Exoplanet Exploration Program Office NASA/Jet Propulsion Laboratory California Institute of Technology Dr. Eric Mamajek Deputy Program Chief Scientist Exoplanet Exploration Program Office NASA/Jet Propulsion Laboratory California Institute of Technology This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. © 2018 California Institute of Technology. Government sponsorship acknowledged. Exoplanet Exploration Program JPL CL#19-0790 ExEP Science Plan, Rev A JPL D: 1735632 Release Date: February 15, 2019 Page 3 of 61 Table of Contents 1. Introduction ......................................................................................................................................................... 3 1.1. The NASA Exoplanet Exploration Program (ExEP) ................................................................................... 4 1.2. Science Investigation Areas Relevant to ExEP Objectives .......................................................................... 6 2. Exoplanet Populations ........................................................................................................................................ 7 2.1. Populations: State of the field ...................................................................................................................... 8 2.2. Populations: Current and upcoming activities ............................................................................................ 12 2.3. Populations: Knowledge needed to inform ExEP Objectives .................................................................... 14 3. Exoplanet Dynamics: Determination of Orbits and Masses......................................................................... 15 3.1. Dynamics: State of the field ....................................................................................................................... 15 3.2. Dynamics: Current and upcoming activities .............................................................................................. 17 3.3. Dynamics: Knowledge needed to inform ExEP Objectives ....................................................................... 19 4. Exozodiacal Dust: Exoplanet Tracer and Obscurer ...................................................................................... 20 4.1. Exozodiacal Dust: State of the field ........................................................................................................... 22 4.2. Exozodiacal Dust: Current and upcoming activities .................................................................................. 23 4.3. Exozodiacal Dust: Knowledge needed to inform ExEP Objectives ........................................................... 25 5. Properties of Target Stars ................................................................................................................................ 26 5.1. Target Stars: State of the field .................................................................................................................... 26 5.2. Target Stars: Current and upcoming activities ........................................................................................... 27 5.3. Target Stars: Knowledge needed to inform ExEP Objectives .................................................................... 32 6. Exoplanet Atmospheres and Biosignatures .................................................................................................... 35 6.1. Atmospheres: State of the field .................................................................................................................. 36 6.2. Atmospheres: Current and upcoming activities ......................................................................................... 37 6.3. Atmospheres: Knowledge needed to inform ExEP Objectives .................................................................. 40 7. Works Cited....................................................................................................................................................... 42 8. APPENDIX A: ACRONYM LIST ........................................................................................................................... 60 1. Introduction Exoplanet Exploration Program JPL CL#19-0790 ExEP Science Plan, Rev A JPL D: 1735632 Release Date: February 15, 2019 Page 4 of 61 1.1. The NASA Exoplanet Exploration Program (ExEP) The NASA Exoplanet Exploration Program (ExEP) is a focused program within the Astrophysics Division (APD) of the NASA Science Mission Directorate (SMD), and defined within the NASA Science Plan [1]. The NASA Exoplanet Exploration Program (ExEP) is managed as a NPR 7120.8 NASA Research and Technology Program. The Exoplanet Exploration Program advances science and strategic planning relate to the broad scientific question “Are we alone?” [1]. ExEP’s three aims are: discovering planets around other stars, characterizing their properties, and identifying candidates that could harbor life Exoplanet exploration is integral to the objectives of the the 2018 NASA Strategic Plan. The 2018 NASA Strategic Plan defines Strategic Objective 1.1: Understand the Sun, Earth, Solar System and Universe. Efforts under Stategic Objective 1.1 are “guided by National priorities and recommendations form the National Academies’s decadal surveys and implemented through a balanced portfolio of programs”, with Science Mission Directorate (SMD) being the lead office. “The success criteria for SMD are progress in answering fundamental science questions, implementing the decadal survey priorities, and responding to direction from the Executive Branch and Congress.” As of 2018, the most recent version of the decadal survey setting priorities for Astronomy & Astrophysics is the 2010 report New Worlds, New Horizons in Astronomy and Astrophysics [2]. Exoplanet science falls under two of the three core contexts of NASA’s first strategic objective: “Discovering the Secrets of the Universe” (where understanding exoplanets is part of understanding “the universe beyond”) and “Searching for Life Elsewhere?”. The 2018 NASA Strategic Plan states: “Observations from SMD’s astrophysics missions have made it clear that habitable planets exist around stars other than the Sun and that such planets are plentiful. Improving techniques and ideas for discovering and characterizing habitable and/or inhabited environments on these planets, coupled with an understanding of the potential false positives for habitability of life, will enable prioritization of exoplanets for targeted follow-up observations. This will help push frontiers in the coming decades of discovery and enable the search for signs of life on worlds that may be capable of harboring life, both within our own solar system and within the galaxy.” The most recent community report relevant to the NASA ExEP is the National Academies’s Exoplanet Science Strategy (ESS) released in September 2018 [3]. The ESS report provides a broad-based community assessment of the state of the field of exoplanet science and recommendations for future investments. The National Academies also released the report An Astrobiology Strategy for the Search for Life in the Universe in October 2018. NASA HQ is currently considering responses to the Exoplanet Science Strategy and Astrobiology Strategy reports, but these are not available at the time of writing. The Astro2020 Decadal Survey is expected to strongly consider the recommendations of the ESS report, and their direction to NASA will guide priorities for the Astrophysics Division and Exoplanet Exploration Program. Exoplanet Exploration Program JPL CL#19-0790 ExEP Science Plan, Rev A JPL D: 1735632 Release Date: February 15, 2019 Page 5 of 61 The 2018 Exoplanet Science Strategy report provided “two overaching goals in exoplanet science”: to understand the formation and evolution of planetary systems as products of the process of star formation, and characterize and explain the diversity of planetary system architectures, planetary compositions, and planetary environments produced by these processes, and to learn enough about the properties of exoplanets to identify potentially habitable environments and their